Written By: Pharmacally Medical News Desk
On September 14, 2025 the FDA approved Enbumyst an intranasal formulation of the loop diuretic bumetanide for short-term treatment of edema associated with congestive heart failure (CHF), hepatic disease (including cirrhosis) and renal disease (including nephrotic syndrome) in adults. Enbumyst is the first FDA-approved intranasal loop diuretic and is intended as an outpatient option that sits between oral and IV diuretics. The FDA has granted this approval to Corstasis Therapeutics Inc. is an innovative biopharmaceutical company providing enhanced outpatient therapeutic option for patients with cardiovascular and renal disease.
Edema
Edema is the buildup of excess fluid in the body, often seen in people with heart failure, liver disease, or kidney problems. It can cause swelling, shortness of breath, and discomfort, and is one of the main reasons patients are admitted or readmitted to hospitals. While oral diuretics are commonly used, some patients cannot absorb them well, and IV diuretics are not always easy to access outside the hospital. Enbumyst, as a nasal spray, offers a practical alternative by providing more reliable absorption and quicker relief, which may help reduce emergency visits and hospital stays.
What Enbumyst is and how it works
Enbumyst contains bumetanide, a potent loop diuretic, delivered through a single-use intranasal spray that allows rapid absorption via the nasal mucosa and provides more predictable systemic exposure than oral tablets. Once Enbumyst is in circulation, bumetanide acts mainly in the thick ascending limb of the loop of Henle in the kidney, where it selectively inhibits the Na⁺-K⁺-2Cl⁻ symporter on the luminal membrane. This transporter is normally responsible for reabsorbing sodium, potassium, and chloride ions back into the bloodstream. By blocking it, bumetanide sharply reduces sodium and chloride reabsorption, which in turn prevents water reabsorption because water follows these electrolytes osmotically. The result is a marked increase in urine output (diuresis) and sodium excretion (natriuresis). Clinically, this helps to mobilize excess fluid that accumulates in patients with congestive heart failure, advanced liver disease, or kidney disease, thereby reducing edema, relieving breathlessness, and improving functional status. The intranasal formulation ensures that patients who cannot tolerate or absorb oral diuretics, or who do not have immediate access to intravenous therapy, still have a reliable option to achieve effective fluid removal.
Enbumyst is approved for the short-term treatment of edema in adults with congestive heart failure, liver disease, or kidney disease, including nephrotic syndrome. Each nasal spray device delivers 0.5 mg of bumetanide, with the usual daily dose ranging from 0.5 mg to 2 mg once daily, not exceeding 2 mg per day. The exact dose and number of devices used are tailored to the patient’s response and clinical condition, with treatment adjusted to achieve the desired diuretic effect while minimizing risks.
Clinical Evidence
The approval of Enbumyst was supported by data from the RSQ-777 clinical trial program, including RSQ-777-02 (NCT05889320), a randomized, crossover study that enrolled 94 healthy adult volunteers. The trial compared intranasal bumetanide with both oral and intravenous formulations to evaluate pharmacokinetics, pharmacodynamics, and tolerability. Results showed that the nasal spray produced urine output and natriuresis comparable to IV administration and more consistent than oral dosing, with less variability in absorption. Importantly, the treatment was well tolerated, with only mild nasal irritation reported in a few participants and no serious safety events. These findings, along with additional pharmacology data, demonstrated that intranasal bumetanide provides effective systemic diuretic action and laid the foundation for its FDA approval.
Safety Profile
The safety profile of Enbumyst is consistent with other loop diuretics, with the most common risks including electrolyte disturbances such as hypokalemia and hyponatremia, along with dehydration, low blood pressure, and changes in kidney function. In clinical studies, the nasal spray was generally well tolerated, with only mild and infrequent nasal irritation reported. As with oral and IV bumetanide, careful monitoring of electrolytes, renal function, and blood pressure is advised, especially in older adults or those on multiple medications. Enbumyst should be used cautiously in patients with severe renal impairment, known hypersensitivity to bumetanide, or in combination with drugs that can further lower blood pressure or alter electrolyte balance.
Key People Opinion and Future Plan
Ben Esque, Chief Executive Officer of Corstasis, said that the FDA’s approval of Enbumyst “represents a meaningful advancement in the treatment of edema for patients and providers.” Dr. Brian Kolski, Chief Medical Director at Corstasis and Director of the Non-Invasive Vascular Lab at the Orange County Heart Institute and Director of Structural Heart Disease at Providence St. Joseph Hospital, CA, emphasized that Enbumyst was designed in direct collaboration with cardiologists to address the practical challenges in outpatient care settings. Meanwhile, Dr. Anuradha Lala-Trindade, Director of Heart Failure Research at Mount Sinai Fuster Heart Hospital in New York, added that Enbumyst “offers the potential to change the standard of care by enabling earlier, outpatient intervention,” which may improve patient outcomes and reduce healthcare costs.
Looking ahead, Corstasis plans to launch Enbumyst in the U.S. in last quarter of 2025, with an initial commercial focus on cardiologists, nephrologists, hepatologists, outpatient heart failure clinics, and integrated delivery networks. They are also working on a market access strategy including real-world outcomes data and payer partnerships to drive adoption. Beyond the nasal spray, Corstasis has secured patents for subcutaneous bumetanide formulations (programs RSQ-786 and RSQ-789), which may allow multi-dose delivery systems possibly with remote monitoring. The plan is to submit those subcutaneous products for approval in the second half of 2026.
References
RSQ-777-02: New Nasal Spray Form of Bumetanide as Effective as Oral and IV Forms in Patients without HF or HF Risk, Americal College of Cardiology, 18 November 2025.
Corstasis Therapeutics Announces FDA Approval of ENBUMYST™ (bumetanide nasal spray) for the Treatment of Edema Associated with Congestive Heart Failure, Liver Disease and Kidney Disease, Business wire, 15 September 2025.
Highlights of prescribing information, ENBUMYST (bumetanide nasal spray)
FDA Approves Enbumyst (bumetanide) Nasal Spray for the Treatment of Edema Associated with Congestive Heart Failure, Liver Disease and Kidney Disease, Drugs.com, 15 September 2025.